Apparently this was a design flaw in the unaugmented human brain, a lagging of consciousness behind intent. - Jon Courtenay Grimwood

There was no way she could know, but Prisoner Zero asked anyway because he was talking to himself; which was all anyone ever did, it seemed to him, talk to themselves while half meanings and misunderstandings fed into the minds of those who thought they were listening.

"We're getting old," he said.
"No," said Paula Zarte. "You are. I'm just not as young as I was."

He had been fighting with himself longer than he could remember and was still not sure who was winning.